For years, engineers and materials scientists have spent countless head
scratching hours and trying to develop a high strength means of joining
composites to metals. Fibre reinforced polymers used by themselves offer high
strength and low weight. But their use in engineering invariably demands that
they are joined to other materials, usually metals.

Poor mechanical performance, low fatigue resistance, and a deep-seated
distrust of the joint's repeatability and integrity have, until now, coerced
designers into over-conservativism. And this negates the very essence of weight
saving. But it could soon be a thing of the past.

With the advent of Comelde the world of composite-to-metal joining looks set
for a surprise. Automotive, aerospace, medicine, oil and gas, renewable energy,
the industrial applications for joining fibre reinforced plastic composites to
metals are countless.

The heart of Comeld's success lies in a metal surface pre-treatment,
invented and patented by TWI, and dubbed Surfi-Sculpte.

The joint is produced by allowing the polyester resin and glass fibre
composite to bond to the prepared surface of, in this case, stainless steel. A
successful joint is created by allowing the polyester resin to bond to the
prepared surface of the stainless steel. In some circumstances, a further
adhesive layer may be called for. Additional standard surface preparations like
etching and priming have also been used to great effect.

The Comeld joint fails at a much higher load and absorbs far more energy
before failure, than a conventional joint of identical dimensions.

This is a joining process of the near future. Formula One racing cars, high
performance military jets, shipbuilders, energy suppliers ...... just about any
industry that uses composites and metals in the same structure will beinterested.

But these are early days in the development of Comeld. So assured is TWI by
the recent and revelatory performance trials that it has launched a group
sponsored project to explore its uncharted capabilities. To learn more, contact:
Faye Smith, TWI. E-mail: faye.smith@twi.co.uk